Even in the field of medical images, the digitalization is advancing, and in the field of digital image radiographing, spatial resolution for reading images is restricted, depending on a reading pixel size of an X-ray detector or on a size of a reading sampling pitch. In this case, there are problems that a subject smaller than the reading pixel size or than the reading sampling pitch cannot be described and that a contour of the subject described turns out to be blurred even in the case of a subject larger than the reading pixel size or than the reading sampling pitch.
In addition, an X-ray detector becomes minute and complicated in terms of a structure, and a volume of data to be handled is increased, resulting in troubles that costs of memory for an X-ray detector and for data processing are increased and time required for data processing is increased.
Although the reading pixel size or the reading sampling pitch is important, it is impossible to achieve an improvement of visibility of a marginal section (contour) subjected to edge enhancement in an image (image used for diagnosis) to be presented finally to a doctor for X-ray interpretation, even if miniaturization alone for the reading pixel size or the reading sampling pitch is attempted.
Patent document 1 discloses a digital phase contrast X-ray image radiographing system provided with a digital-X-ray image detector to obtain a digital image of a phase contrast X-ray image in which the reading pixel size of this digital-X-rays image detector is almost equal to the phase contrast edge enhancement half band width of a phase contrast X-ray image.
Moreover, for example, when a phase contrast radiography is performed by the use of CR (Computed Radiography), FPD (Flat Panel Detector) an so on and thus obtained image data are outputted to a film or a viewer, if B=A/M in which M represents a photographing magnification at the time of phase-contrast radiography (magnifying power), A represents a minimum control unit (pixel size) at the time of reading and B represents a minimum control unit (pixel size) at the time of outputting, it may be possible to match a reading pixel and an output pixel with 1:1. In this case, since a reduction interpolating process becomes unnecessary, there has been well known no problem that a part of side edge image applied with an edge enhancement is disappeared at the time of interpolation treatment and image deterioration may not be caused                [Document 1] Japanese Patent Unexamined Publication No. 2003-180670        